In International Patent Application PCT/US 84/00226 (International Publication No. WO 85/03750) a torsion spring cartridge assembly is disclosed which may be used for supporting wheels on trailers or other vehicles, and has significant advantages over its prior art. A corresponding U.S. application of the same title exists: U.S. application Ser. No. 781,149, filed Aug. 14, 1985, now abandoned.
As one disadvantage of the structure disclosed in the International Application, it is relatively expensive to manufacture. Additionally, if subjected to excessive loads or bumps, the torsion spring cartridge assembly of the International Application can rotate beyond its mechanical limits, causing breakage of the torsion rods used therein.
Also, because it is desirable for improved functioning of the torsion spring cartridge assembly of the type of the International Application to have torsion rods that do not rotate, the rods are shown to be of rectangular cross-section, being retained at their ends in rectangular holes in a pair of spaced hubs. Rectangular or other non-circular holes in a hub of the type used in the International Application can be made only by broaching, an expensive process. Furthermore, the rectangular torsion bars must be peened for optimum utility, and are capable of mechanical failure to a greater degree than cylindrical rods, since their rectangular corners are more subject to failure under torsion stress.
The invention of this application overcomes the disadvantages described above. Additionally, the torsion bar suspension unit of this invention may be easily installed and replaced on a vehicle or any other desired object. Thus, the invention of this application provides great economies in torsion bar suspensions for wheels or any other desired use, for example, as a suspension system for trailers or the like. Additionally, large objects may have the suspension system of this invention installed under them for the temporary addition of wheels. Then, they may be rolled to a desired location, and the suspension systems may be removed and used elsewhere.
Additionally, the amount of torsion can be adjusted by varying the number of torsion bars used in the system, so that the same torsion bar suspension unit may be easily modified by simply adding or subtracting torsion bars as may be desired. Furthermore, upon axle failure following abuse of the system, torsion bar systems in accordance with this invention have much less tendency to cause loss of control.